INVESTIGADORES
ESTEVEZ Jose Manuel
artículos
Título:
Anticoagulant activity of a unique sulfated pyranosic (1,3)-β-L-Arabinan through direct interaction with thrombin
Autor/es:
P. V. FERNÁNDEZ, I. QUINTANA, A. S. CEREZO, J. J. CARAMELO, L. POL-FACHIN, H. VERLI, J. M. ESTEVEZ, M. CIANCIA.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Lugar: Bethesda, Maryland; Año: 2012
ISSN:
0021-9258
Resumen:
A highly sulfated 3-linked b-arabinan (Ab1) with arabinose in the pyranose form was obtained from
green seaweed C. vermilara
(Bryopsidales). It comprised major amounts of units sulfated on C-2 and C-4,
and constitutes the first polysaccharide of this type isolated in the pure form
and fully characterized. Ab1showed anticoagulant activity by global coagulation tests. Less sulfated
arabinans obtained from the same seaweed, have less or no activity. Ab1 exerts
its activity through direct and indirect (antithrombin- and heparin cofactor
II-mediated) inhibition of thrombin. Direct thrombin inhibition was studied in
detail. By native PAGE it was possible to detect formation of a complex between
Ab1 and human thrombin (HT). Ab1 binding to HT was measured by fluorescence spectroscopy.
CD spectra of the Ab1-complex suggested that ligand binding induced a small
conformational change on HT. Ab1-thrombin interactions were studied by
molecular dynamic simulations using the persulfated octasaccharide as model
compound. Most carbohydrate-protein contacts would occur by interaction of
sulfate groups with basic amino acid residues in the surface of the enzyme, being more than 60% of them performed by the exosite 2-composing
residues. In these interactions the sulfate groups on C-2 showed to interact
more intensely with thrombin structure. In contrast, the disulfated
oligosaccharide does not promote major conformational modifications at the
catalytic site when complexed to exosite 1. These results
show that this novel pyranosic sulfated arabinan Ab1 exerts its anticoagulant
activity by a mechanism different to those found previously for other sulfated
polysaccharides and glycosaminoglycans.